The invention relates to a pump, such as a power-steering pump, with a flow-regulating valve device and an injector device, where one or more fluid jets streaming off the flow-regulating valve generate suction to pull fluid back into the pump from a suction pipe connection or from a reservoir. The pump supplies the power-steering system in a motor vehicle and an additional fluid-driven device such as a hydraulic motor for a cooling fan. Pumps of this general kind belong to the known state of the art. For example, in a known version of a power-steering pump where the fluid flow is used for the additional purpose of powering a hydraulic fan motor in the ventilating system of a motor vehicle, the fluid returning from the hydraulic motor is introduced into the reservoir tank through a second injector device a short distance upstream of the point where the reservoir is connected to the flow regulation valve injector of the pump. Thus, the pump has two injectors that are arranged in immediate proximity of each other. It has been found that the fluid streams of this dual injector arrangement can influence each other at high rpm-rates, i.e., at high flow rates. The interaction between the fluid streams can interfere with the charger effect that takes place in the suction area, and it can cause cavitation which produces noise.
The invention therefore has the objective to propose a configuration for a pump that supplies a power-steering device and a second consumer device such as a hydraulic fan motor, so that the aforementioned problems will not occur within a broad range of operating situations.
A pump according to the present invention, e.g., a power-steering pump, has a flow-regulating valve device and an injector device. A fluid stream directed from the flow-regulating valve to the injector device generates a suction effect in the injector device and thereby pulls fluid into the intake area of the pump from a suction pipe connection or from a reservoir. The pump supplies the power-steering system in a motor vehicle and an additional fluid-driven device such as a hydraulic motor for a cooling fan. In the pump according to the invention, at least one separate fluid-return orifice is arranged in addition to the injector outlet channel in the intake area of the rotating assembly inside the pump. At least a portion of the fluid returning from the additional fluid-driven device enters the intake area of the rotating assembly through the one or more separate fluid-return orifices.
One embodiment of the inventive pump has two separate return orifices leading into the intake compartment in addition to the injector outlet channel. Regardless of whether the pump has one or more than one stream of return fluid in addition to the injector stream, the preferred arrangement according to the invention requires that the one or more return streams and the injector stream enter the intake area of the rotating assembly independent of each other through separate orifices. According to the invention, the return streams must be prevented from influencing the injector stream.
As a further preference according to the invention, the arrangement of the orifices of the return channels in the intake area is symmetric in relation to the injector outlet channel. In particular, the return-channel orifices are arranged laterally to the right and left of the injector outlet channel as seen in the axial direction of the rotating assembly.
The improved apparatus, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawing.